Adenine phosphoribosyltransferase (APRT) is a purine salvage enzyme that catalyzes the transfer of ribose-5-phosphate to adenine, creating AMP and pyrophosphate. Although mammals synthesize purines de novo, parasitic protozoa must scavenge purines from their host. Rapidly dividing cancer cells also rely heavily on the purine salvage pathway for their purine source. APRT is an important enzyme enabling parasites and tumor cells to recycle host purines, and for that reason, it is a promising target for drugs aimed at treating cancers and parasitic infections.